Effects of centrally and systemically administered indomethacin on body temperature in exercising rats

Subcutaneous and intracerebroventricular (icv) injections of indomethacin were used to test whether prostaglandin synthesis is essential for the exercise-induced increase in a rat's body temperature. At an air temperature of 24 degrees C, male Wistar rats ran on a treadmill at 10-15 m/min 20 min after 300-micrograms icv injection or 60 min after 15-mg/kg sc injection of indomethacin or of control vehicle. The rectal temperature (Tre) of control rats in 17 control experiments increased by 1.0 degree C during exercise, whereas the Tre of the rats pretreated with intracerebroventricular indomethacin increased by only 0.4 degrees C. Threshold Tre for tail vasodilation was significantly lower in rats pretreated with indomethacin than the control rats (38.4 +/- 0.1 vs. 38.9 +/- 0.1 degrees C), but O2 uptake did not differ between indomethacin-pretreated and control rats. Subcutaneous injection of indomethacin did not affect the body temperature, tail vasomotor activity, or O2 uptake of exercising rats. Intracerebroventricular indomethacin did not affect Tre or tail vasomotor activity of rats resting at ambient temperatures of 24 and 28 degrees C. Present results suggest that prostaglandin synthesis is required for the vasoconstrictive effect of exercise on skin blood vessels and thus for the exercise-induced elevation of body temperature.